As scientific heroes go, Humphry Davy is up there with the best of them. He is revered not for his experiments with laughing gas or electrochemistry but because he demonstrated that science could be put to good, practical use. In 1815, he invented the miners’ safety lamp, a simple but ingenious piece of technology that saved lives and enabled miners to dig deeper and produce more coal. But if Davy’s lamp was the brilliant application of science he claimed, why does his collection of papers contain no lab notes or letters related to his work on it? Historian Frank James suspects that someone destroyed them. Why? Because they would have told a story that cast Davy in a different light.
HUMPHRY DAVY was the most famous chemist in Regency England, a knight of the realm with friends in the highest places. A romantic at heart, his only ambition was to use his scientific knowledge to improve the lives of his fellow beings – as he did so brilliantly when he invented the miners’ safety lamp.
That, at least, was the image Davy cultivated. “He was also unpleasant, self-obsessed, devious and manipulative,” says Frank James, historian at London’s Royal Institution, where in the early 1800s Davy ruled the roost. Even so, his reputation as a national hero has endured for two centuries, and his safety lamp is one of the iconic objects in the history of science. Yet from the start, says James, Davy deliberately distorted the facts. The tale of Davy’s scientific triumph was a triumph for spin and a vicious campaign to squash anyone who questioned the official version of events.
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The familiar version of the story goes like this. In the summer of 1815, Davy was on holiday in Scotland when he was approached by the Society for Preventing Accidents in Coal-Mines to solve a problem of national importance. Too many coal miners were dying in explosions sparked off when their lamps ignited pockets of firedamp (methane) that plagued the deeper parts of mines. This lethal combination of flame and firedamp was holding back expansion of the industry.
By October Davy was back in his lab, and within two weeks had discovered that a gas “will not explode in a small tube the diameter of which is less than the 8th of an inch”. The trick then was to ensure that the only way any gas could enter a lamp was through very narrow passages.
By the end of the year, Davy had found that all it took to make a naked flame safe was to replace the lamp’s glass chimney with a cylinder of brass gauze because the holes were too small to permit any explosion. The mine owners were grateful – to the tune of £2500 of silver plate – and the Prince Regent made him a baronet.
Davy was none too pleased when other inventors claimed to have made their own safety lamps. The most serious claim came from George Stephenson, a young mining engineer at Killingworth colliery near Newcastle. According to Stephenson’s supporters in the north, he was testing his version of a safe lamp in the pit while Davy was still experimenting with gases in London. An unedifying priority dispute developed in which each man claimed the other had pirated his ideas, although neither applied for a patent or went to court to prove his claim. “I never thought of such a thing,” protested Davy. “My sole object was to serve the cause of humanity.” The dispute was never resolved. But Davy ended up with virtually the entire credit for the invention of the safety lamp, says James. “He had better PR and more powerful friends.”
James didn’t set out to dent Davy’s reputation. He wanted to know how Davy had made the leap from science to technology. What experiments had Davy carried out? What observations had led him to his successful design? A search through Davy’s papers got him nowhere: he expected to see lab notes and letters about the lamp, but found none.
James turned to other archives. At the Royal Society in London he found several early drafts of Davy’s original paper on the lamp. He also tracked down letters that Davy had written to others outlining his progress, in some cases including an early “sketch” of the work. The contents of these suggested that when Davy claimed his lamp was first and was the result of scientific research, he wasn’t being entirely honest – a fact that might explain why his papers hardly mention the lamp. “There was strong motivation for Davy or his executors to get rid of anything among his papers that cast doubt on his version of events,” says James.
Davy had evidently been panicked into getting his results into print. His paper was due to appear in the Royal Society’s Philosophical Transactions in March 1816. But fearing Stephenson might publish first, he had it shoehorned into the December issue of the society’s Philosophical Magazine – less prestigious but quicker. And in a costly move, just before the more formal version appeared in the Transactions, he insisted on pulling out a plate of illustrations showing various models of lamp he had developed. The designs left out were those that most resembled Stephenson’s. Although there is no evidence that Davy stole Stephenson’s ideas, he clearly didn’t want to invite comparison. “Stephenson probably did invent it first,” says James. The reason Davy didn’t try to patent the lamp owed nothing to altruism: he didn’t dare risk a clash in court because he might have lost.
With the question of priority lingering in the background, Davy took every opportunity to stress the scientific nature of his lamp, as if that made it somehow superior. So what was so scientific about it?
Among the documents James examined are drawings of the many prototypes of Davy’s lamp. They show that Davy tinkered with his lamps until he had something that provided good light without causing explosions. There is no eureka moment, at which a breakthrough in scientific understanding led to an innovative new design. The only contribution from science was the discovery that gases don’t explode in narrow tubes, which Stephenson and others had also worked out. “Davy’s method of developing the lamp was no better than Stephenson’s,” says James. “He had all the resources of metropolitan science to call on but in the end he came up with the same technology as someone down a pit in the north-east – and that really annoyed him.”
Besides belittling Stephenson’s efforts, Davy had political reasons for exaggerating the scientific nature of his invention. When the Royal Institution was founded in 1799, its remit was to encourage the practical application of science. So far, nothing much had come of it. The technologies driving the expansion of industry were almost exclusively the products of engineers and mechanics, practical men rather than scientists. Davy and other members of the scientific elite were under pressure to prove that science was of some use to society – and worth supporting. The lamp was just the proof they needed.
Davy’s fellow scientists were easy to convince. “He insisted that scientific knowledge had driven the invention, and they swallowed it because it shored up their own idea of what they were all about,” says James. From there, it wasn’t hard to persuade the world at large. Soon everyone believed Davy could do a few experiments and solve the day’s pressing problems. It was a belief that led to his eventual downfall.
“He didn’t dare risk a clash in court because he might have lost”
In 1823, the British Navy Board asked Davy to find a way to prevent the corrosion of copper sheathing that protected the bottoms of its ships. In the lab he found that corrosion stopped if he reversed the electrochemical polarity of copper by soldering pieces of zinc or cast iron to the sheathing. Trusting Davy’s ability to turn science into technology, the navy rushed to fit “Davy protectors” to its ships. Unfortunately, they also removed the anti-fouling properties of copper so the ships were quickly disabled by the weight of weed and barnacles on their bottoms. This time, Davy’s science had been brilliant, but the technology was a disaster. “It was a failure on a grand scale,” says James.